Brick shapes for building blast-furnace linings and the like



-Dec-I?, 1929. J..c. MOREHEAD 1,740,258

BRICK SHAIS FOR BUILDING BLAST FURNACE LININGS AND THE LIKE 4Filed July 12, 1928 4 sheets-sheet `-1 MM "MW Dec. 17, 1929.

J, C. MOREHEAD BRICK'SHAPES FOB` BUILDING BLAST FURNACE LININGS AND THE LIKE Filed July 12, 1928 4 Sheets-Sheet 2 WITNESSES Dec. l?, 1929.

Filed July 12, 1928 4 Sheets-Sheet 5 WITNESSES l' lNvENToR MMM. am c, WWA

l ww ll gy@ Dec.. 17, 1929. 1. c. MOREHEAD 1,740,258 BRICK SHA1-ES FOR BUILDING BLAST FURNCE LIN- NGS AND THE LIKE' Filed July 12, 1928 4 sheets-sheet 4 lNVvENTOR k n 3%. f-

M20-MIN Patented. Dec. 17, 1929 UNITED STA-'rss maza PATENT OFFICE JAMES C. MOREI-IEAD, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO INLAND-STUART LININGS, INCL, OF PITTSBURGH, PENNSYLVANIA, A

CORPORATION OF DELAWARE BRICK SHAPES FOR BUILDING BLAST-FUENACE LININGS AND THE LIKE Application filed July 12,1928. Serial No. 292,305.

The invention relates to linings forblast furnaces and the like, and especlally to bricks for building such structures.

Blast furnace linings and similar struc- 'tures usually comprise circular courses of design is arbitrary. The different sizes are not related to one another, or to the structures built therefrom. In consequence, much chipping and fitting is required to maintain the proper curvature when using these bricks. Thus they are not adapted for use in accurately building structures of every curvature; the bricks do not break joints in a proper manner in the rows of a course and between the courses; and it is impossible to space all of such bricks properly. So far as I am aware, no bricks have been devised thus far of which a few simple shapes and sizes sur'iice to properly construct linings of any desired thickness and diameter.

An object of the invention is to provide a plurality of standard brick shapes so related in shape and size that furnace linings of any size greater than a given minimum diameter may be built from a small number of shapes and sizes.

lAnother object is to provide a plurality of standard brickshapes so related to each other and to a given basic furnace opening as to minimize the number of different keys and straights required to construct a lining equal to or greater than that of the basic opening, and of any desirable thickness. K

A further object is to provide a pluraity of standard brick shapes so related to each other and to a minimum basic openingy that variations in diameter of opening may be attained in substantially ideal manner, using a few different sizes and shapes, with little, i-f any,

chipping or fitting.

Still another object is to provide a :means of relating the shape and size of keys and straights to each other and to circularstructures to be built therefrom, in such a manner as to accomplish the foregoing objects, and which provides means for determiningin advance the manner in which the brick shall be laid in any given structure to produce a substantially perfect lining.

It is among other objects of the invention to provide standardized related b ick shapes of the type and by the means referred to which may be made to closely approximate the standard sizes now in use, which may be laid accurately and without the use of any other shape of brick than those provided by the invention,^and which substantially eliminate the arbitrary .spacing and the chipping heretofore necessary.

The invention may be described in connection with the accompanying drawings, which represent a preferred embodiment. Fig. l is a diagrammatic elevation of a blast furnace; Fig. 2 shows the manner of designu ingl key bricks, in this case four in number; Figs. 3 and l are perspective views of two straights; Fig. 5 is a horizontal section through a cylindrical portion of the furnace, such as the hearth, taken on line VmV, Fig. l; Fig. 6 is a vertical section taken on line vll-VI, Fi g. 5, these two views showing the lining in place; Fig. 7 is an enlarged view cfa horizontal sector of a lining, similar to VII-VII, Fig. 5, showing the numb-er of brick of different sizes per row and a manner of disposino' the same in all possible row positions, not staggered, of a course; Figs. 8 and 9 are respectively views similar to Fig. 7 showing two consecutive courses of brick and an end elevation of the samefor an opening` of minimum diameter; and Figs. l() and ll are views similar to Figs. 8 and 9, but for an increased diameter, such as on line X-X, Fig. '1. y Y

The-invention is predicated upon the use of a small number' of basic keys and development bricks so related to each other and to a selected basic furnace opening as to serve for linings of any diameter equal to or greater than that .chosen as basic. Their'relation valso is .such that'linings may be made of 'any Ef.. l

thickness which is a multiple of a chosen brick length factor.

' i keys comprise two bricks which l an annuius of the chosen basic They have the same al angle and inner width, and their the, which are different, represent intei multiples of a given lengtn factor. The utcr width of these basic keys is, of course, dependent upon their length, because of their sector basis. rlhe inner width of these keys is chosen such that when an integral number' are laid side by side they will exactly turn a circle of the basic diameter. The basic diameter is the minimum furnace opening which can be built from these brick, and is preferably chosen :is the smallest which is commonly used.

The development brick are used inV conliunction with the basic keys for building the outer rows of a course, and also in connection with basic keys for expanding the basic opening. The development brick are definitely related to the basic keys. This relation is such that given combinations will exactly occupy a selected extent, such as an integral sector of the lining, and also such that the two types may be used in selected combina* tions to provide any desired increment in diameter greater than, or decrement down to, the basic diameter. Preferably the development brick comprise two growth-keys and two straights, although basic keys may in some cases be used without growth keys. Likewise, four straights may be used instead of two. The inter-relation between all of these bricks and their manner of use follow certain delinite relations fully set forth hereinafter.

Having reference now to the drawings, Fig. l is a conventional representation of a blast furnace comprising a refractory lining 2 forniing stack and hearth portions l and la surrounded by a metallic outer shell 3, and a bosh portion l. The lining, which-embodies the invention, comprises horizontal circular courses each comprising a plurality of concentric rows of bricks designed and laid in a definite manner.

The lining comprises basic keys and development brick. According to the preferred embodiment the development brick include both growth keys and straights, two of each type being used The straights may comprise two used for filling, and two for expanding. Filling straights are used for filling and complot-ing the outer rows of a course, 'and cxpanding straights are used to expand the basic diameter. However, in order to reduce the number of brick'st-yles, it is preferred to make a single type of straights which will satisfactorily accomplish both purposes. The relations existing between the various brick are as follows, reference being had to Figs. 2, 3, 4l and 7.

The basic keys l and la are laid out as sectors of an annulus of inner dia-meter D, where micas-e l) is selected basic or minimum furnace or li ing opening. The same central angle a is included by each of the keys, and each has the same inner width w. This inner width is chosen such that an integral, desirable num ber n of the basic keys will exactly lill a ring of diameter D. This follows readily from the equation:

The number n is chosen to give w a suitable value., preferably approximately that now used.

The length of the keys is based upon a length factor L, which may be and preferably is, a commensurate divisor of the brick lengths now used. Keys l and la are, for purposes of securing proper breaking of joints, of different length. These lengths are integral multiples of the factor L and in the example shown the length of key l is 2L, and that of 1n is 3L, although other values may be chosen. The width of the outer ends.

of the basic keys depends upon their length.

For example, if e' is the nth part of the circumference of a circle whose radius 1s L,

and if the radius is increased by L, the circumference increases by an amount equalto z'. Thus the outer widths are w+2z for key l, and url-3a' for key la. From this it will be understood that the basic keys will exactly fill the inner rows of basic minimum diameter D, and that this is the smallest opening which can be built from those keys.

The growth keys 2 and 2 are likewise sectors of an annulus, concentric with but of greater' radius than that of the basic ring by an amount equal to bL where b is equal to or an integral multiple of a factor b described hereinafter. These keys are laid out with the same central angle and of the same lengths as the basic keys, and their inner widths will be alike and equal to w-tbz' as appear from the foregoing considerations The outer lengths, likewise, will be Aw+ (bul-2M for the keys 2, and w+ (lf-t3) z' for the keys 2a.

The straights are shown in Figs. 3 and 4l, as rectangular bricks 3 and 3L whose lengths are respectively 2L and 3L. For maintaining uniformity of construction these brick are also of equal width, represented as kt', where is an integral multiple of the factor b described hereinafter. The thicknesses of the keys and straights may be those now used. f

For purposes of illustration, let D 14 feet and L=Ll1/ inches, a common divisor of the two standard lengths heretofore used, so that the lengths 2L and 3L are those now used, or 9 and 13.5. inches. ln order to provide Cil basic keys '-haying an inner width approximating 'present vInfact-ice, a convenient integral number of which will till the @basic ring, 'ii is in 'this case chosen as 1M. From the equation it follows that 20, the inner width of keys 1 'and l, is 4.63 inches. It also follows that i202@ inches; and if 5'; 6, the inner width ofthe growth keys 2 and 2%(10 1L Z/z) is 6.118 inches. A suitable wid th for the straights is given by assuming :24,V in which lcase :=5.-9 inc-hes, or approximately 6 inches, the width now used. Other dimensions may of course be used where desirable or necessary,'the various sizes being readily determinable.

` The beneiits of the invention are secured in part by the manner of assembling these brick to v`form a structure of given size ot opening or wall thick-ness, or to vary those dimensions, or the uniformity of the opening, and in all cases to provide 'for breaking of all joints. This manner of disposing the bricks Vis understood most readily by consid ering a sector or block of a course, which rep resents an integral part of the course. To this end, a sector Vil-VII, Figs. 5 and 7, is chosen, which Icontains a convenient number ot 4basic keys in its inner row. rlhis .num-

ber is represented by the previously men- Y tioned factor b. which must be an integral portion ot n. Each row in a given sector of a course will, in accordance with the invention. contain b basic keys, growth keys, or basic and growth keys combined.

The blockshown in Fig. 7 is taken as being ot basic minimum diameter, that is, its inner diameter is that of the ring which forms the basis for the ybasic keys. The factor 7) is in this case equal to 6, this value being suitable ,tor lay-ont purposes, and also in this base 71:47). Six basic keys 1 will exactly lill the inner row of this block; and there will be E,

or 19 such blocks .in the illustrative example, each being an exact duplicate of the others. The succes Yive rows in the block will vbe made up by replacing basic by growth keys, each of the latter increasing the inner width of the row by an amount equal to (wrba')-w, or 7, f,..which is in this case 6i, or 1.488 inches. llvlhen. through this operati a row contains only growth keys, further expansion is attained by the combined use of basic and growth keys and straights. It will be understood that vwhere basic keys 1 or growth keys 2 are referred to, keys 1?? and 2 respectively, may be used, their inner widths being the as that ofthe .corresponding key.

' nalle i he built up vto any desired iv ich is aymultiple of the length table @heise of the bricks, and

factor y ,l

because of their relation to each other, these bricks will accurately fill every row up to any desired wall thickness.

The inner width ot' .each row of a sector or biock is, according to the invention, equal, or substantially equal, to the outer width off the next row inwardly. That this object is actually and readily achieved is shown lby F 7, in which the bricks are numbered as described above. The inner row consists of six basic keys l, so that its outer width is 6 (w -l- 2i) or 6u) 122'. The next row consists of four basic keys 1, and `two growth keys 2, and its inner width equals 4w+2(e016), which reduces to 610+ 127i, the outer width of the inner row. It can be shown readily that each row outwardly follows the same progress as developed for rows 1 and 2.

The number of the various brick required for each row of the blocks, either of the eX- aniples given, or in any other case, can be calculated readily. Let =the number of basic keys, i/ the number ot' growth keys, and e the number of straights in a row, and let g? be the row position, or number of unit lengths L irom the inner end of the row considered to the inner end of the inner row, which latter is assumed to be a zero position, Then .rtg/2b, or the keys per row,'whic'h is constant t'or every row in the sector. `The number of bricks for any row will be found by means of the equation ,b (u1-tip) :me -l-y/ (i0 .-'r bz') -fr elsa' which reduces to y PZiMH/it@J+2/#Mw and since mty- 6:0, this becomes anw/Habt and since according to definition b and are alwaysintegral factors of 7c, and the total number of keys in any row of a sector is constant, it is always possible to readily iind integral values of y and e which will satisfy this equation.

The layout of Fig. 7 is used to show how the bricks may be disposed in successiverows of a course to give any desired thickness with each row tltting the adjacent rows properly. As shown there, the end joints do not break in an ideal manner. This feature oit the invention is secured in the manner shownin Figs. 8 and 9, in which the end joints break inf'a fully proper manner, both vertically and horizontally. These views'represent a block similar to that discussed hereinabove,

the opening' again being of basic diameter. Two courses 10 and 11 are shown, theilowei` being represented by dottedlines in Fig. 8. Thelower course l0 of the block is started by laying siXbasic keys l. The outer width, as before, is (SMH-152i." The next row of this .course is displaced laterally about one-third oi a brick width, asseen in Fig. `8.y This row consists of the longer keys la and 2, and to secure perfect fit this row will consist of four basic keys 1aM and two growth keys 2, their total inner width being Gioi-12e'. Successive rows in this course will then be laid in the manner explained previously, as shown in the drawing. The brick in any row are of the same length, and straights are added when necessary. The basic and growth keys, and straights, in rows subsequent to the inner row are disposed as symmetrically as possible to assist in breaking joints. l

The next course, 1l, commences with an inner row of six basic keys la, their outer width being` 6w+l8z1 This is followed by a row of three keys 1a and three growth geys 2n, whose inner width totals 610-1182', the same procedure being followed up to the last row, when the course is completed by a row of bricks 1, 2, and 3, as shown. The inner row of this course is displaced about one-third of a brick width with respect to the inner row of the course below it. and successive rows are disposed in the manner described Y for course l0.

From this is will be seen that the preferred practice is to lay successive courses in which the limiting rows of a course are of different length from those in the same position in adjacent courses. Also, all the `-bricks in any one row are of the same length, and adjacent rows are laterally olfset. In laying successive courses, the inner rows are staggered yabout one-third of a brick width, and by virtue of this, the spacing in consecutive rows of a course, and overlapping of vertical rows, all joints break in a proper and theoretically perfect manner. In building up a cylindrical lining following Fig. 8, the course laid on course ll will be similar to course 10, and so on, to the height desired. Other layouts intermediate the limiting rows may be used with equallyv satisfactory results. j

The examples discussed thus far have related to linings having a cylindrical opening of the basic minimum diameter. The preferred manner of expanding this diameter to obtain larger openings is to insert one or more straights in the inner row of one or more blocks, the number of keys reinaining the same, and a similar number of straights are inserted in all subsequent rows of the block or blocks. These are, of course, extra straights over and above those which would normally be used in outer rows. Each straight, by virtue of the relations previously explained, inserted in the inner row will increase the diameterbf the opening by an amount Aequal to In the illustrative case chosen this is equal to 1.894 inches. By so adding straights the diameter can, by regular increments, be made as large as desired. Where al plurality of straights are used for this purpose, they are spaced at approximately regular intervals about the circle.

This could be accomplished by using an expanding straight, of different width than the filling straight, to give a larger or smaller increment than the straights 3 and 3a. However, as pointed out previously, satisfactory results are obtained, and with fewer sizes of brick, by using the straights illustrated for both purposes.

This manner of expanding is illustrated in Figs. 10 and l1 in which each row of the courses l0a and l1a contains a straight l5 or 15a for expanding, lthe layout being otherwise as shown in Fig. 8. Although these straights are, as stated, preferably straights 3 and 3a, a different numeral is used to represent them, to indicate that they are used in addition to the brick disposition of Fig. 8.

The method just described may be used to attain larger diameters for cylindrical openings, or to expand gradually in making sloping or conical openings. The reverse of the foregoing procedure, that is the removal of straights, is used for decreasing the diameter of an expanded opening. Another means of laying the brick to form sloping inner walls, where the use of straights might produce too abrupt changes,

is as follows: A basic key l (or la) in the inner row is replaced by a growth key 2 (or 2a), and the successive rows calculated in the manner previously explained, adding` b to the left side of the equation. The value of is, of course the circumferential increment produced by the substitution referred to. That is, it is to2-w, where w and 'L02 are respectively the widths of the basic and growth keys. Or, (wl-bz') -w=bz'. In the example given, bz equals 6i, and the straights are 24a' wide. Thus the use of a growth key instead of a basic key will produce but one-fourth the increase in diameter that is produced by adding a straight.

It will be understood that other brick dispositions may be used than those illustrated and described, and that other concrete values may be used than those given for purposes of illustration, without departing from the scope of the invention. Likewise it will be understood that the invention is not limited to the use of four keys and two straights, Six keys can be used, for example, and the use of four straights4 as in present practice has been discussed. Also,

the invention comprises the case whereerecting blast furnace linings and similar structures, of which a' minimum number of sizes and types may be' used for building` a structure of any size greater than a basic minimum diameter, whichV latter may be of any Adesirable size. They may bevused for building cylindrical or slopingawalls with equally satisfactory results. The structures obtained are more satisfactory 'than those heretofore erected, because morel perfect bonding and fitting is possible. Also the invention givesy greater economies in erection costs and otherV expenses. By providing a minimum number of standard sizes which will accurately fit any desired condition,l smaller stocks of sizes are necessary, estimating can be done with great' accuracy, and ydefinite layouts can be made-which can be Afollowed ,with little, if any, chipping or fitting'.y This increases the speed of erection.V j

il. A circular tapering furnace liningl built up from basic key bricks comprising sectors of a ring and growth key bricks, saidvbricksA being laidinlhorizontal courses each comprising a plurality of concentric rows,r said basic keys including two sizes of different length and of the same inner width, an integral number ofqwhich will turn a circle of minimuiirb'asic dia-meter., said growth, key bri'ck comprising two 4sizes of equal inner width and of different lengths equal to those ofthe basic key bricks, all four of said brick sizes having their longer sides radial to' a vcommon center, each row of a course containing an equal number of keys,' the inner diameter of on'e row being the same as the outer diameter of the next row inwardly,the rows outwardly in a course being increased in `diameter by the use of growth key brick, 4the brick in successivev rows of a course breaking joint, each row of la course being offset lat*r era'lly with respect to consecutive rows and to those in adjacent courses so as to break joints vertically, and the rows of successive courses overlapping whereby vertical joints 'at the ends of the brick are'broken. l,

, A tapered brick furnace lining circular in horizontal section comprising horizontal courses each coiisistingof a plurality of concentric rows of bricks, .said brick comprising straights and keys, the'straights including twoY lengths of equal width, the keys comprising a basic set and a growth set, said basicvset comprising sectors of a basic ringv in two lengths of equal inner width, an integral number of which when laid side by side will turn a basic circle equal to a minimum furnace opening, said growth 4set comprising sectors 'ofa ring concentric with and of greater diameter than said basic ring and alsoin twol lengths of equal inner width,the lengths of said keys being the same as thatjof the straights, each row in a: course containing the same number of keys, the inner diameter of a row of a course being equal to th-e outer diameter of the next row inwardly, the di' am-eter of the rows up to that of the growth ring being increased by lreplacing basic keys by gro'vvthfkeys, and beyond that diameter also inserting straights, said straights each 'increasing the diameter by an amount equal te the width divided by 1r, the bricks in adjacent rows of a courseV breaking joint, the

number of which will turn a circle equal to ai basic minimum furnacev diameter, and a growth set in two lengths of equal inn-er width also sectors of a ring which is concentric with and of greater diameter than said basic ring,j said lengths being the same iii eachpseteach row of a course containing the same number of keys, andr thevrows in a course outwardly from its inner row being developed by substituting growth keys for basic keysl and adding straights, according tr 'i where b ifs' the number of keysv per row in a given: integral sector of a course, p is the row# position, il is the increase in width' of a key per unit length factor, y and a are respectivelyY theV number of growth keys and straights, is tli-e width of a straight, and

il is the difference in width of the basic andav growth keys.

t. taperingb'rick furnace lining circular in horizontal section comprising horizontal courses each consisting of a plurality of con-V centric yrows of brick, said brick comprisingi straights and keys, the straig its including two related lengths of equal width, the keys comprising a basic set and av growth set, said basic' set being sectors in two lengths of equal inner width of a basic ring the diameter of` which is that of a basic ii'iinimuni furnace opening, said growth set comprising sectors in two lengths of equal inner width of a growth ring concentric with and of greater diameter than said basic ring, the lengths of said keys being the same as the leiigti'i of the straights the basic and growth keys being eqiuangulai, the inner row of a course of asie diameter containing only basic keys,

and the successive rows of said course having growth keys substituted for basic keys the number of growth keys increasing as the diameter of a row approaches the diameter of the growth ring and beyond thediameter bricks in successive courses being overlappedk ot the growth ring, each row having added thereto straights with combinations of said keys, the number ot' keys in each row ot a course being constant, the limiting i'ows ot ysuccessive courses Comprising brick of dif-` vring the diameter ot' which is that of a basic minimum furnace opening, said growth set comprising sectors in two lengths ot equal inner width oi' a growth ring concentric with and ot greater diameter than said basic ring,

` the lengths ot said keys being the same as the lengths ot the straights, said basic and growth keys being equiangular, the inner row of a courseof basicv diameter containing only'A basic keys, the number ot' keys in each row of a course being constant, the inner diameter oi' each row successive to an inner row up to that ot' the growth ring being substantially equal to the outer diameter ot the next row inwardly and having growth keys combined `with basic keys, the number of growth keys increasing as the diameter approaches that ot the growth ring, and those beyond thel O'rowth ring containing straiglits with ycoinbinations or said keys, and the limiting rows of successive courses being of dilerent length brick.

6. A furnace lining according to claim 5, the rows ot a course intervening between its limiting rows being chosen so as to break joints vertically with the bricks in adjacent courses, and all the bricks in a row being of y the same length.

7. A brick furnace lining of non-uniform diameter circular in section comprising successive courses each comprising a plurality of concentric rows otl brick, said brick comprising key bricks and straights, said straights comprising two lengths of equal width, said key bricks comprising basic keys and growth keys, said basic keys being sectors in two lengths and of equal innei width of a f ring ot' basic minimum diameter, said growth keys comprising sectors in two lengths and ot equal inner width of a ring concentric with and ot greater diameter than said basicV ring, all of said lengths being integral multiples of a common divisor, and all of said keys having the same central angle, said bricks being adapted for the construction of linings` of any diameter equal to or greater than that of the basic i'ing,andot any thickness being ats in'a course containing thev same number of' keys,'and'-the bricksi-n successive courses being staggered and overlapped, whereby all joints are broken.

8. A Vfurnace lining which is tapered and which is lcircularv in horizontal cross section made up of horizontal courses of brick arranged in concentric rows, the brick comprising a set of basic keys in two lengths, the keys being sectors ot a circle of'basic diameter, a

set of growth keys in two lengths corresponding'to-the basickeys and being sectors of a circle of greater diameter than the basic circle, the basic keys and the growth keys being equiangular, avset of straight brick of `two llengths corresponding to the longths of the f keys, each row in a course whose diameter is greater than the diameter of the basic circle and less than the diameter of the growth circle being comprised ot basic and growth key bricks, and beyond the diameter of the growth circle comprised of basic-and growth keys and straight brick, the rows of every coursecontaining the same number of key bricks.

9. Afurnace lining which is tapered andV ywhich is circular in horizontal cross section Amadeupfot horizontal courses of brick arranged in concentric rows, the brick comprising a set of basic keys in two lengths, the keys being sectors of a circle of basic diameter, a set of growth keys in two lengths corresponding to the basic keys and being sectors of a circle of greater diameter than the basic circle, the basic keys and thegrowth keys being equiangular, a set of straightV brick of two -lengths corresponding to the lengths of the keys, each row in a course whose diameter is greater than the diameter of the basic circle and less than the diameter ot the growth circle being comprised of basic and growth keyy bricks, and beyond the diameter of the growth circle comprised of basic and growth keys and straight brick, the rows of every course containing the same number of key bricks, the rows of greater diameter than the diameter of the growth circle having one additional straight block for each given increment of increase in diameter, those rows beyond the diameter of the growth circle wherein the inincrement of increase in diameter is insufficient to provide for an additional straight having combinations of basic and growth keys by which the diameter is expanded while the bricks remain closely spaced.

l0. A tapering brick furnace lining circular in horizontal section comprising horizontal courses each consisting of a plurality of concentric rows of brick,said brick comprising straights and keys, the straights including two-related lengths-of equalwidt-hs,

les

the keys comprising a basic set and a growth set, said basic set being sectors in two lengths of equal inner width of a basic ring, the diameter of which is that of a minimum basic furnace opening, said growth set comprising sectors in two lengths and of equal inner width of a growth ring concentric with and of greater diameter than the said basic ring, the lengths of said keys being the same as the lengths of the straights, the basic and growth keys being equiangular, the inner row of a course of basic diameter containing only basic keys, other rows of greater diameter being developed first by substituting growth keys 'for basic keys, and beyond the diameter oic the growth ring by adding straights with combinations of said keys, the number of keys in each row of a course being constant, the rows of successive courses comprising brick of different lengths, and the brick in successive courses being laterally offset with respect to those in adjacent courses whereby vertical joints are broken.

In testimony whereof, I sign my name.

JAMES C; MOREHEAD. 

